Sand and salt are poured into a single beaker. the result is a mixture because

Sand and salt are poured into a single beaker. the result is a mixture because they are not chemically combined. When water is added to the sand-salt mixture, salt dissolves in water, and sand does not. When the liquid is poured through a filter, salt water passes through the filter. The remaining salt water is heated until water is boiled off (evaporated) leaving salt behind. 

I'm not sure but i will try to find out

Hydrogen is the most abundant element on the periodic table..hope it .